Method of preparing sulfite cellulose.



CARL BACHE-WIIG, 01F PORTLAND, MAINE.

METHOD OF PREPARING SULFITE CELLULOSE.

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lose, of which the following is a specificapenetrated.

tion.

This invention has for its object a novel method of preparing sulfite cellulose, by which the yield from the Wood is increased, being from four to six per cent. higher than when prepared in the ordinary manner with bisulfite liquor. Heretofore, the pieces or chips of wood have been placed in the d1- gester and subjected to the action of a bisul- I'ite liquor at a more or less high temperature, and for longer or shorter periods of time. The bisulfite liquor ordinarily employed is composed of water, sulfurous acid,

together with calcium or sodium or magnesium or mixtures of these. In accordance with my invention, I add a small quantity of sodium chlorid, (NaCl), say from a of 1% to 3%, which forms a part of the base for making the bisulfite liquor, that is to say, it may be associated with either of the well-known bisulfite liquors, as calcium, sodium, or magnesium, or mixtures thereof. The sodium chlorid maybe used in several ways as for instance, it may be put into the digester with the chips of wood, or it may be injected as a solution of any degree of concentration into the digester during the operation, or it may be added to the calcium, sodium, or magnesium, or mixtures thereof, or to their solutions, or it may be placed in the sulfurous acid reclaiming tanks.

By using sodium chlorid as a part of the base of a calcium bisulfite liquor (CaHSOQ the following advantages are obtained First; partially, a sodium sulfite is formed, which acts better upon the wood fiber than the calcium sulfite.

Second; chlorids of calcium and magnesium are formed, which have a bleaching efi'ect on the fiber.

Third; the. sodium chlorid itself has a softening efi'ect on the fiber walls, permitting the fibers to be more quickly and deeply Fourth; the sodium chlorid also binds or Specification of Letters Patent.

Fatented Sept. 25, Cllfiil't.

Application filed November 7 1914. Serial No. 870,903.

holds the sugar in the wood, in the early stages of the cooking operation, thus preventing the ligneous matter from passing in the solution too quickly, so that the action on the fiber will be much more gentle or less harsh, thereby resulting in the formation of less hydro-cellulose with a correspondingly increasing yield.

Fifth; experience has shown that a lower temperature may be employed during the cooking operation.

There is a physical reaction from the sodium chlorid to which I attribute, at least in part, the many. advantages gained by its use.

With a sodium bisulfite liquor, (NaI-ISO or a magnesium bisulfite liquor, (MgHSOQ or a bisulfite li'quor containing a mixture of hit calcium, sodium, or magnesium, correspondchlorid during the cooking operation.

3. The method herein described of preparing sulfite cellulose, which consists in cooking small pieces of wood in a magnesium bisulfite liquor and in injecting a very small quantity, say less than 5%, of sodium chlorid during the cooking operation.

4. The method herein described of preparing sulfite cellulose, which consists in cooking small pieces 01"? wood in a sodium bisulfite liquor and in injecting a very small quantity, say less than 5%, of sodium chlorid during the cooking operation.

In testimony whereof, I have signed my name to this specification, in the presence of two subscribing witnesses.

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Witnesses:

E. A. WAKELY, WM. Srncnem. 

